#include<iostream>
#include<string>

using namespace std;

class Solution {
public:
    string removeDuplicates(string s) {
        string ret;
        for (auto ch : s)
        {
            if (ret.size() && ch == ret.back())
            {
                ret.pop_back();
            }
            else
            {
                ret += ch;
            }
        }
        return ret;
    }
};

int main()
{
    return 0;
}